instructure/canvas-lms · warning · Translation::TextTooLongError

TextTooLongError

Error message

TextTooLongError

What it means

Translation#handle_cedar_errors maps Cedar client ContentTooLongError-class exceptions to Canvas's Translation::TextTooLongError. It is raised when the submitted text/HTML exceeds the translation service's maximum content length, so the request is rejected before any translation is produced.

Solutions

1. Truncate or chunk long content below the service's length limit before translating
2. Rescue Translation::TextTooLongError and show a 'content too long to translate' message
3. Translate per-message/per-section instead of aggregating large bodies
4. Pre-check content length against the documented Cedar limit before calling

Example fix

# before
Translation.translate_text(text: long_body, tgt_lang: 'es', options: opts)
# after
if long_body.length > MAX_TRANSLATION_LENGTH
  chunks = long_body.scan(/.{1,#{MAX_TRANSLATION_LENGTH}}/m)
  translated = chunks.map { |c| Translation.translate_text(text: c, tgt_lang: 'es', options: opts) }.join
else
  translated = Translation.translate_text(text: long_body, tgt_lang: 'es', options: opts)
end

# pre-check content length against the service limit
raise Translation::TextTooLongError if content.length > MAX_TRANSLATION_LENGTH

begin
  Translation.translate_text(text: content, tgt_lang: tgt, options: opts)
rescue Translation::TextTooLongError
  Rails.logger.info("Content too long to translate (#{content.length} chars)")
  nil
end

When it happens

Trigger: translate_text/translate_html called with content whose length exceeds the Cedar service limit, and CedarClient raising an exception whose class name matches /ContentTooLongError/ — e.g. translating an entire long discussion post or a large HTML document in one call.

Common situations: Translating long discussion entries, submission comments, or whole-page HTML; limits lowered on the translation service; concatenated user content exceeding caps; callers chunking incorrectly or not at all.

Understand the failure class

Background: payload too large / request exceeds maximum size: why libraries cap bytes and how to fix oversize payloads — this error's family across 50 libraries.

Related errors

• Translation::SameLanguageTranslationError
• SameLanguageTranslationError
• UnsupportedLanguageError
• Cedar rate limit exceeded for #
• e.message

AI-assisted analysis of instructure/canvas-lms@1c9f0bb801 (2026-09-15). Data as JSON: /api/errors/1cae54071e88826b. Report an issue: GitHub.

Appendix: source

Thrown at lib/translation.rb:139

      if source == target
        InstStatsd::Statsd.distributed_increment("translation.errors", tags: ["error:same_language"])
        raise Translation::SameLanguageTranslationError
      end
    end

    def collect_translation_stats(src_lang:, tgt_lang:, type:)
      tags = %W[type:#{type} source_language:#{src_lang} dest_language:#{tgt_lang}]
      InstStatsd::Statsd.distributed_increment("translation.invocations", tags:)
    end

    def handle_cedar_errors
      yield
    rescue => e
      case e.class.name
      when /SameLanguageTranslationError/
        raise SameLanguageTranslationError
      when /ContentTooLongError/
        raise TextTooLongError
      when /UnsupportedLanguageError/
        raise UnsupportedLanguageError
      when /ValidationError/
        raise ValidationError
      else
        raise TranslationError, e.message
      end
    end
  end
end

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